High-power conversion efficiency in a strained InGaAs/AlGaAs quantum well laser

Abstract
A strained quantum well laser with a front-end power conversion efficiency exceeding 33% under continuous-wave operation is demonstrated. The laser structure, grown by atmospheric pressure organometallic vapor-phase epitaxy, consists of a 70-Å In0.2Ga0.8As quantum well active region with graded index separate confinement heterostructure. Lasing wavelength is 930 nm, and the front-end differential quantum efficiency is 58% for broad-area oxide stripe lasers with a high-reflection coating on the rear facet. Front-end, continuous power outputs greater than 1 W are available. Although these strained quantum well lasers have threshold currents as low as lattice-matched GaAs quantum well lasers, their internal quantum efficiencies appear to be reduced, thus limiting the maximum attainable conversion efficiency.